What side effects may I notice from receiving Methadone Hydrochloride?

Side effects that you should report to your doctor or health care professional as soon as possible:

-allergic reactions (skin rash, itching or hives; swelling of the face, lips, or tongue)
-confusion
-heartbeat rhythm changes (trouble breathing; chest pain; dizziness; fast, irregular heartbeat; feeling faint or lightheaded, falls)
-kidney injury (trouble passing urine or change in the amount of urine)
-low adrenal gland function (nausea; vomiting; loss of appetite; unusually weak or tired; dizziness; low blood pressure)
-low blood pressure (dizziness; feeling faint or lightheaded, falls; unusually weak or tired)
-serotonin syndrome (irritable; confusion; diarrhea; fast or irregular heartbeat; muscle twitching; stiff muscles; trouble walking; sweating; high fever; seizures; chills; vomiting)
-trouble breathing
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

-constipation
-dry mouth
-nausea, vomiting
-tiredness

This list may not describe all possible side effects for Methadone Hydrochloride. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.